The present invention relates to the field of regulator circuits, and in particular, to a circuit that sub-regulates and senses an input voltage from a common connection point such that the circuit has a minimum number of external connections.
An integrated circuit is usually constructed from a small chip of semiconductor material upon which active and passive components are constructed. The active and passive components are connected together to form a functioning circuit. An integrated circuit is generally encapsulated in a plastic housing (case) with pins that are accessible for connection to external electronic circuitry. Input signals are connected to the integrated circuit via selected input pins. The input signals are processed by the active and passive components that are designed to operate within a limited range of supply voltages.
Battery powered devices often employ integrated circuits to regulate the power provided by a battery cell. Regulators are often used where the input power source is unregulated or clean power is required in a noisy environment. The regulator is often contained within the integrated circuit.
As batteries discharge, the loss in power can effect portions of the integrated circuit dependant on the battery power. The integrated circuit can suffer from poor performance when the battery power decreases below a certain level. External measurement circuitry is often added to the integrated circuit in order to measure the decrease in battery power that is delivered to the integrated circuit. By compensating the operation of the integrated circuit for the decrease in delivered power, poor performance can be avoided.
Charging devices for charging batteries are also used as alternate power sources when coupled to the integrated circuit. Poor performance or a damaged battery may result from either over-charging the battery cell or charging the battery at an excessively high rate. Additional circuitry is often included to regulate the amount of charge delivered to the battery as well as the rate at which the battery is charged.
In accordance with invention, the above and other problems are solved by a method and apparatus that sub-regulates and senses an input voltage with minimum connections. The reduction in connections permits the use of the freed connections for other purposes related to the apparatus or an associated circuit, and thereby increases the utility of the apparatus and the associated circuit.
Briefly stated, an electronic circuit produces a measurement signal and a regulated power supply from a single common connection to a raw power supply signal. The electronic circuit can be used as a module in a power control circuit, such as a circuit for charging a battery cell. For -integrated circuit (IC) applications, the electronic circuit has a single pin connection for accepting signals or connecting to elements external to the IC. The electronic circuit sub-regulates the potential at the common connection or node using a voltage regulator. A control output of the voltage regulator is used to regulate the power supply. The power supply can be held at a relatively constant DC potential when compared to the raw power supply signal. To produce the measurement signal, a drop in potential from the potential at the common node is measured by a sense circuit. The measurement signal is produced as a result of the drop in potential. The measurement signal is associated with value of the raw power supply signal such that the raw power supply signal can be calculated from examining the measurement signal. The measurement signal can be used by another circuit to generate one or more control signals. The control signals can then be used for applications in other circuits. One example of the application of the electronic circuit is in the charging circuit for a battery cell. The control signals can be used to regulate the rate and amount of charge delivered to the battery cell.
In one embodiment, an apparatus is directed to generating a measurement signal and a regulated voltage supply from a raw power supply signal having a corresponding raw voltage that is provided to the apparatus through a single connection point. The apparatus includes a voltage monitor circuit that is arranged to produce a feedback signal in response to a voltage at the single connection point. A regulator circuit is arranged to produce the regulated voltage supply in response to the feedback signal and a reference signal. A sense circuit is arranged to produce the measurement signal in response to the voltage at the single connection point, wherein the measurement signal is associated with the corresponding raw voltage of the raw power supply signal such that the measurement signal and the regulated voltage supply are produced from the single connection point with minimized external connections.
In another embodiment, an apparatus is directed to providing a measurement signal to a charge control circuit that selectively delivers charge to a battery cell from an unregulated power supply through a single common input pin in response to a charge control signal. The apparatus includes a potential monitoring circuit that is arranged to produce a sense signal in response to a potential at the single common input pin. A potential regulating circuit is arranged to produce a regulated power supply in response to the potential at the single common input pin and the control signal. A sense circuit is arranged to produce a measurement signal in response to the potential at the single common input pin and a potential of the regulated power supply, wherein the measurement signal is associated with the unregulated power supply and the charge control signal is responsive to the measurement signal such that the charge control circuit delivers charge to the battery cell in response to the measurement signal.
In yet another embodiment, a method is directed to generating a measurement signal and a regulated power supply from a raw power supply signal having a corresponding raw voltage that is provided to a single port. The method includes monitoring a voltage of the regulated power supply to produce a feedback voltage, comparing the feedback voltage to a reference voltage, producing a control signal in response to the comparison of the feedback voltage to the reference voltage, producing the regulated power supply in response to the control signal, and producing the measurement signal in response to a voltage at the single port and the voltage of the regulated power supply such that the corresponding raw voltage can be determined from the measurement signal.
In still another embodiment, an apparatus is directed to producing a measurement voltage and a regulated power supply having a regulation voltage from an unregulated power supply voltage that is provided to the apparatus through a single connection, wherein a charge control circuit utilizes the measurement voltage to provide a controlled charging potential that is delivered to a battery cell. The apparatus includes a means for monitoring that monitors the regulation voltage to produce a feedback voltage. A means for comparing produces a control signal in response to a comparison between the feedback voltage to a reference voltage. A means for regulating regulates the regulation voltage in response to the control signal. A means for measuring produces the measurement voltage in response to a voltage at the single connection and the regulation voltage such that the unregulated power supply voltage can be determined from the measurement voltage.
A more complete appreciation of the present invention and its improvements can be obtained by reference to the accompanying drawings, which are briefly summarized below, to the following detail description of presently preferred embodiments of the invention, and to the appended claims.